422 
Synopsis of the Birds 
a slight rudimental furrow, sub-basal, lateral, concave, lon- 
gitudinal, linear, pervious, covered partially by the feathers 
of the front advancing far on the bill : tongue moderate, 
linear, acute, entire. Head oblong, depressed, narrowed be- 
fore, rounded posteriorly ; eyes small : neck short, moderately 
robust : body stout, elongated. Feet placed very far back ; 
lower extremity only of the tibia apparent ; tarsus one-fourth 
shorter than the middle toe, slender, compressed, carinated 
anteriorly : middle toe longest; inner by one third shortest, 
subequal to the tarsus ; webs not very broad : nails compres- 
sed, moderately curved, acute ; middle one larger, dilated 
internally into a sharp edge. Wings short, narrow, acute; 
first primary longest. Tail very short, rounded, of twelve 
feathers. 
Female smaller, similar to the male. Young differing from 
the adult, but almost similar to their winter dress. Moult 
twice a year, changing the colors of their plumage. Colors 
black and white. 
Keep always near the sea, leaving it only when breeding, not 
found on fresh water except when straying inland. Walk with 
difficulty, and only when obliged to cross the ice, in an erect 
posture. Flight short, though rapid, just skimming the sur- 
face of the water: reaching the top of high rocks by jump- 
ing and fluttering from point to point. Swim and dive ad- 
mirably, even beneath the ice, driving their submarine prey 
by employing their wings as fins, appearing to fly under 
water. Feed principally on fishes. Breed socially in the 
clefts of perpendicular rocks: lay without the least preparation 
on the naked rock, one or two eggs at most, disproportion- 
ately large, and with a very hard shell : feed their young 
with fishes, which they carry to them in their bill. Eggs, 
feathers, and flesh of the young, sought after. 
Inhabit the Arctic seas, whence they migrate in summer to 
the temperate coasts all round the globe. Our five species 
are the only well ascertained of the genus. 
